Repeated seismic surveys from the Norwegian Sea using new streamer technology

Eiken, Ola; Aronsen, Hans; Osdal, B.; Furre, Anne-Kari; Klefstad, L.; Nordby, L.H.

doi:10.1190/1.1817006

Cited by 6 publications

(4 citation statements)

References 3 publications

(3 reference statements)

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“…However, it is generally acknowledged ͑e.g., Ebrom et al, 1997;Calvert et al, 2002Calvert et al, , 2004Curtis et al, 2002;Eiken et al, 2002;Kragh and Christie, 2002͒ that the nonrepeatability effect resulting from mispositioning source-receiver locations in the repeated survey can be more significant than the production-induced 4D seismic signal.…”

Section: Effect Of Mispositioning On Traveltime Shift and Reflectivitmentioning

confidence: 99%

Discrimination between phase and amplitude attributes in time-lapse seismic streamer data

Spetzler

Kvam

2006

GEOPHYSICS

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Time-lapse seismic experiments aim to obtain information about production-related effects in hydrocarbon reservoirs to increase the recovery percentage. However, nonrepeatability problems such as acquisition differences, overburden effects, and noise are often significantly stronger than the imprint of production changes in time-lapse seismic data sets. Consequently, it is very difficult to appraise the changes in petrophysical reservoir parameters over time. We introduce a 4D monitoring approach based on the spectral ratio method. This method produces two time-lapse attributes: the relative change in reflection coefficient and the traveltime shift at reflecting interfaces. These attributes can be used for appraising production-related changes in the subsurface. The approach corrects for time-invariant nonrepeatability effects in the overburden and source-receiver coupling problems in time-lapse surveys. The validity of the method is limited to structurally simple overburden and reservoirs with weak lateral variations. First, we validate the methodology using a synthetic time-lapse seismic experiment. Next, we apply the method to a real time-lapse data set from the Troll West gas province in the North Sea. In the real example, we could not detect movement in the fluid contact of 5-15 m. The expected change in amplitude is less than 10%, which is probably below the background noise level for this data set.

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Section: Effect Of Mispositioning On Traveltime Shift and Reflectivitmentioning

confidence: 99%

Discrimination between phase and amplitude attributes in time-lapse seismic streamer data

Spetzler

Kvam

2006

GEOPHYSICS

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“…In this example, only Time-lapse changes between 2001 and 2003 will be considered. In order to reduce uncertainty related to Time-lapse seismic monitoring, the Qmarine technology from WesternGeco was used in the monitor surveys (Eiken et al, 2002).…”

Section: Time-lapse Seismic Acquisition and Processingmentioning

confidence: 99%

Integrated Reservoir Management Approach: From Time-Lapse Acquisition to Reservoir Model Update at the Norne Field

et al. 2005

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TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractAs in many other fields in Statoil, Time-lapse (or 4D) seismic data is one of the important tools used for monitoring the Norne field. However, in order to reduce uncertainties, an integrated multidiscipline approach involving geophysics, reservoir engineering, geology and petrophysics has been successfully applied. As a result, a better history matched reservoir model was obtained by improving the consistency between the reservoir simulator results and the observed 4D seismic data. This led to an increased understanding of the reservoir drainage and hence contributed to the process of identifying and prioritizing infill-drilling targets at Norne.

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“…Harris and Adler (1999) investigated how the quality of the seismic data affects the accuracy of estimates of seismic variations in time‐shifts, phase rotation or amplitude variation between time‐lapse seismic data sets. Eiken et al . (2002) showed that repeated streamer positions were possible with new streamer technology that allowed for horizontal steering of the streamers.…”

Section: Introductionmentioning

confidence: 99%

Sea‐bed diffractions and their impact on 4D seismic data

Grude¹,

Osdal

Landrø³

2012

Geophysical Prospecting

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A B S T R A C TA sea-bed reflection is used to estimate changes in water layer velocities between timelapse seismic surveys. Such corrections are crucial in order to obtain high-quality 4D seismic data. This might be a challenge in areas where rough sea-bed topography creates sea-bed diffractions that interfere with the sea-bed reflection, as in several of the northern fields in the Norwegian Sea. These diffractions and diffracted multiples are difficult to attenuate during data processing and become a source of noise in time-lapse data.In this work we study how cross-correlation analysis of time-lapse seismic data at a sea-bed reflection may be perturbed by the presence of diffractions. The seabed topography from the Norne field is used in 2D finite difference modelling to explain some of the observed variation in a water layer time-shift in field data. We find that a rough sea-bed and the diffracted energy it induces cause residual noise on the 4D data. The variation to the water layer time-shift increases with sea-bed complexity and is amplified by interaction with other sources of non-repeatability like water column variations, mis-positioning and strength of the ice scours creating the diffracted energy. Time-shift variations with mis-positioning and velocity changes between the surveys seem to best explain the observed variation in the time-shift for time-lapse seismic field data from Norne. I N T R O D U C T I O NThe importance of repeatability in time-lapse seismic data has been emphasized by the industry for many years. Landrø (1999) studied how repeatable a fixed-tool vertical seismic profiling (VSP) survey might be and how the repeatability changes with inaccuracies in source positioning. Harris and Adler (1999) investigated how the quality of the seismic data affects the accuracy of estimates of seismic variations in time-shifts, phase rotation or amplitude variation between time-lapse seismic data sets. Eiken et al. (2002) showed that repeated streamer positions were possible with new streamer technology that allowed for horizontal steering of the stream- * E-mail: sissel.grude@ntnu.no ers. Kragh and Christie (2002) examined the use of two repeatability metrics in assessing the similarity of two sets of repeat 2D lines acquired with a marine point receiver system. Eiken et al. (2003) showed that towing streamers with narrower than normal cross-line separation followed by spatial interpolation in processing can increase the repeatability. Calvert (2005) discussed various issues related to 4D reservoir monitoring and characterization. Hatchell, Wills and Landro (2007) showed that guided waves in a water layer can be used to accurately measure the water velocity changes at different times in a field. Lippard, Osdal and Riste (2010) tested to what degree 3D migration compensates the effect of mis-positioning in the final 4D image. Landrø, Digranes and Strønen (2001) combined traveltime and amplitude information from timelapse seismic data to map pressure and saturation changes for a non-compacting reserv...

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Repeated seismic surveys from the Norwegian Sea using new streamer technology

Cited by 6 publications

References 3 publications

Discrimination between phase and amplitude attributes in time-lapse seismic streamer data

Discrimination between phase and amplitude attributes in time-lapse seismic streamer data

Integrated Reservoir Management Approach: From Time-Lapse Acquisition to Reservoir Model Update at the Norne Field

Sea‐bed diffractions and their impact on 4D seismic data

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